L & C IT Consultants

CPU fan connector

This
3-pin / 4-pin connector is
dedicated for providing the
power source and displaying
the CPU fan speed.

CPU fan 3-pin IDC male connector at
the motherboard

Pin

Name

1

GND

2

+12V

3

Sense tachometer

CAUTION:
Do not place a jumper on this
connector; serious board damage
will result if the 12v is
shorted to ground.

Chassis
and CPU fans may use either
3-pin or 4-pin power connectors.3-pin connectors are usually used for the smaller
chassis fans with lower power
consumption.4-pin connectors are usually used by CPU fans
with higher power consumption

Fan has a 3-pin power connector; desktop board
has a 4-pin fan header:

Note:
when using a 3-pin power connector
with a 4-pin fan header, the
fan will always be on; there
is no fan control.

Fan has a 4-pin power connector; desktop board
has a 3-pin fan header: